8-thiomethylergolines

ABSTRACT

8-Thiomethylergolines, prolactin inhibitors.

United States Patent Kornfeld et al.

451 Aug. 26, 1975 S-THIOMETHYLERGOLlNES Inventors: Edmund C. Kornfeld: Nicholas J.

Bach. both of Indianapolis. ind.

Assignce: Eli Lilly and Company, Indianapolis Ind.

Filed: June 6, 1974 App]. No.: 477,136

U.S. Cl 260/285.5; 424/261 Int. Cl i. C07d 43/20 Field of Search 260/2855 Primary Examiner-Donald G. Daus Axsistam Examiner-Mary C. Vaughn Atlorney, Agent, or FirmJames L. Rowe; Everet F. Smith {57] ABSTRACT 8-Thiomcthylergolines, prolactin inhibitors.

6 Claims, No Drawings S-TIIIOMETHYLERGOLINES BACKGROUND OF THE INVENTION Compounds based on the ergoline ring system (I):

have a surprising variety of pharmaceutical activities. For example. lysergic and isolysergic acid are 8- carboxy-(i-methyl-. \"-ergolines (9. IO- didehydroergolines). The amides oflysergic acid. many of which have valuable and unique pharmacologic properties. include the naturally occurring oxytocic alkaloids ergocornine. ergokryptine. ergonovine. ergocristine. ergosinc. ergotamine etc. and synthetic oxytocics such as mcthergine as well as the synthetic hallucinogen lysergic acid diethylamide or LSD The amides of b-methyl-8carhoxyergoline. known generically as dihydroergot alkaloids. are oxytoeic agents of lower potency and also lower toxicity than the ergot alkaloids themselves. Ergotamine. a A"ergoline. has been used in the treatment of migraine anad recently. both ergocornine and 2-bromoaergokryptine have been shown to be inhibitors of prolactin and of dimethylbenzanthracene (DMBA)-induced tumors in rats. according to Nagasawa and Meites. Proc'. Soc. [:Ivp'rl. Biol. Med. I35. 469 I970 and to Heuson et al.. EllfU/J. J. Cancer. 353 (1970). (See also US. Pat. Nos. 3.752.888 and 3.752.814).

D-6-methyl-8-cyanomethylergolinc was first prc pared by Semonsky and eo-workers. ('oll. (bet-Ii. (ht n1. ('ommmL. 33. S77 (1968). and its use in preventing pregnancy in rats was published by the same group in iN'urure, 22l. 66b I969). (See also US. Pat. No. 3.732.231) The compound was thought to interfere with the secretion of hypophysial leuteotropic hormone and the hypophysial gonadotropins. It was also sug gested that the compound inhibited the secretion of prolactin. [See Seda et al.. Reprod. Fert.. 24. 263 (1971 and Mantle and Finn. id. 44] )I. Semonsky and co-workers, (01], ('zec'lz. Chem. ('0mm., 36. 220 (1971). described the preparation of D-6-methyl-8- ergolinylacetamide. a compound which is stated to have anti fcrtility and anti-lactating effects on rats. The effect of these compounds in neoplastic disease is unknown. Ergolines with a thiomcthyl substitucnt or a dc rivative thereof have not previously been prepared.

SUMMARY OF THE INVENTION This invention provides 8-thiomethylergolines of the formula:

wherein R is H. CN.

phenyl. or alk'.

R is H. Cl. or Br.

alk is C -C alkyl; and

R" and R' when taken singly are H; and. when taken together with the carbon atoms to which they are attached. form a double bond.

The term alk in the above formula. comprehending as it does C -C alkyl groups. includes the following radicals: methyl. ethyl. n-propyl and isopropyl. In the above formula. when R" and R' are hydrogen. the compounds are generically denominated as D-o-alkyl- R-thiomethyl (or mercaptomethyl) ergolines. When R" and R' are taken together with the carbon atoms to which they are attached to form a double bond. the rcsulting compounds are known generically as D-o-alkyl- S-thiomcthyl or mercaptomethyl-9. I didehydroergolines. Compounds illustrative of the scope of the above formula include the following:

D-Z-chlorolmethyl-t'l-propionylthiomethylergoline D2chloro-o-methyl-8butyrylthiomethyl9.IU-

didehydroergoline D Z-chloro-G-methyl-S-phenylmercaptomethyl-Q.ll)-

didehydroergoline D-2-bromo-b-methyl-X-phenylmcrcaptomethyl-Q.ll)-

didehydrocrgoline D-Z-chloro-h-methyl-R-ethylmercaptomethyl- ).l0

didehydroergoline D-(i-methyl-8-n-propylmcrcaptomethylcrgoline D-(i-methyl-8isopropylmercaptomethylcrgoline and the like.

The compounds of this invention in which R is other than H are prepared by reacting via nucleophilic displacement an ester of a D-(i-alkyl-tlhydroxymcthylergolinc or of a 9.l(l-didehydroergoline. optionally substituted at C-2 with chlorine or bromine. with salts ofthiocyanic acid. thiophenol. a thioalkanoic acid (alk-COSH) or an alkylthiol (alk-SH Esters use ful as starting materials in the above synthetic procedure include the mesyl (methanesulfonyl). the ptolucnesulfonyl (p-tosyl) and the like esters formed with the hydroxy group of 8-hydroxymethyl-6- methylergoline. X-hydroxymethyl6-methyl-9.ll)-

didehydroergoline or of a Z-halo derivative ofeither of the above compounds. These mesyloxy and p-tosyloxy derivatives are either known compounds or can be prepared from the corresponding hydroxy derivatives by processes available in the art. In carrying out reactions with thiophenol or with an alkyl thiol. the sodium salt of the mercaptan group is usually formed. using sodium methylate or sodium hydride. Also. an alkali metal thiocyanate is used. The nucleophilic displacement reaction is carried out in an inert solvent such as dimethyl formamide (DMF). dimethylsulfoxide (DMSOJ or the like. Ordinarily. the reaction is carried out at room :mpcrature of ifdesired by heating to a temperature in te range from room temperature to l()t)C. The prodcts of the reaction are customarily isolated by stanard techniques and purified by chromatography. prefrably over florisil. The compounds of this invention in :hich R is H are prepared by hydrolysis in base of the orrcsponding compound in which R is The compounds of this invention are white crystaline solids and form pharmaceutically acceptable salts with nontoxic acids. These pharmaeeutically accept- .ble salts are included within the scope of this invenion. Nontoxic acids useful in forming the salts of this nvention include such inorganic acids as hydrochloric icid. nitric acid. phosphoric acid. sulfuric acid. hydroiromic acid. hydriodic acid. nitrous acid. phosphorus tcid and the like. as well as non-toxic organic acids in- :luding aliphatic mono and dicarboxylic acids. phenyl- .ubstituted alkanoic acids. hydroxy alkanoic and alkanlioic acids. aromatic acids. aliphatic and aromatic sul- 'onic acids. etc. Such pharmaceutically-aeceptable aalts thus include sulfate. pyrosulfate. bisulfate. sulfite. visulfite. nitrate. phosphate. monohydrogenphosphate. lihydrogenphosphate, metaphosphate. pyrophosphatc. :hloride. bromide. iodide. fluoride. acetate. propit iate. decanoate. caprylate. acrylate. formate. isobutyr- .ite. caprate. heptanoate. propiolatc. oxalate. malonate. succinate. suberatc. sebacate. furmaratc. maleatc. butyne-l.4-dioate, hexyne-Lo-dioate. benzoate. chlo in each experiment the rats were killed by decapitation. and l5ll .d aliquots of serum were assayed for prolactin. Each male rat received an intraperitoneal injection ol 2.0 mg of reserpine in aqueous suspension 18 hours before administration of the ergoline derivative The purpose ofthe reserpine was to keep prolactin levels uniformly elevated. The derivatives were dissolved in lllfil ethanol at a concentration of it) pg/ml. and were injected intraperitoneally at a standard dose of pglkg. Each compound was administered to a group of ill rats. and a control group of ill intact males received an equitalent amount of it) percent ethanol. One hour after treatment all rats were killed by decapitation. and the serum was collected and assayed for prolactin as previously described. The results were evaluated statistically using Students r test to calculate the level of significance. 1.

The difference between the prolactin level of the treated rats and prolactin level of the control rats. di vided by the prolactin level of the control rats gives the percent inhibition of prolactin secretion attributable to the compounds of this invention. The table which follows gives prolactin inhibition percentages for a series of compounds coming within the scope of Formula ll above. In the table. column I gives the name of the compound; column 2. the dose level of the compound in the prolactin inhibition test; column 3. the percent prolactin inhibition; and column 4. the level of significance.

The invention is further illustrated by Examples l-6 which follow.

Table Prolactin [1" Name ol Compound Dose inhibition \alue [)o-methyHi-phenylmercaptomethyl ).lU-didcltydroergoline HI pg fill 05 D-h-methyl-ltmethy lmercaptomethyl-9.l(ldidehydroergohne It] pg h] ,(ll D-hanelhyldiareetyllhiomethylergolinc lll pg 40 .Ul [)Js-melhyLil-mereaptomethylcrgoline 10 pg 66 ,t|l)l D-o-methyl-tl-melhylrnercaplo' methylergoline ll) #g 49 t)(ll D-I'chloro-hanethyl-ti-metltylmereaptometh lcrgolinc lil pg 46 .0lll l)-n-methyLX thiocyammethylergoline lll 1g 4| .Ulll D-h-methyl-i4-acel}lthiomethyl J.ltLdidehydroergolinc ill pg 44 .tll

EXAMPLE I robenzoate. methylbenzoate. dinitrobenzoate. hydroxybcnzoate. methoxybenzoatc. phthalate. terephthalate. benzcnesulfonates. toluenesulfonate. ehlorobenxcne. sulfonate. xylenesulfonate. phenylacetate. phenylpropionate. phenylbutyrate. citrate. lactate. B- hydroxybutyrate. glycollate. malate. tartrate. methanesultonate. propanesulfonates. naphthalene-l-sulfonate and naphthalenc-Z-sulfonatc and like salts.

The compounds of this invention are useful as prolactin inhibitors. The inhibition of prolactin secretion by the compounds of this invention is evidenced by the following experiment: Adult male rats of the Spraque' Dawlcy strain weighing about 200 g. were used. All rats were housed in an air-conditioned room with con :rolled lighting (lights on o a.m. pm.) and fed lab :how and water ad libitum.

Preparation of D-b-Methyl-8Thiocyanomethylergolinc PXAMPLE 2 Preparation of Dlvmethyl-R-phenylmercaptomethylergoline A suspension of l0 g. of D-(vmethyl-K h droxymethylergoline in 200 ml. of pyridine as prcpared. To this suspension was added slowly a solution containing 6.0 ml. of mcthanesull'onyl chloride and 200 ml. of pyridine. The resulting mixture wa stirred at room temperature under a nitrogen atmosphere for about one half hour and was then poured Into 2 F l. of saturated aqueous sodium bicarbonate The alkaline aqueous layer was diluted to 6 liters with water. and the diluted layer allowed to stand at room temperature. D- 6-methyl-8-mesyloxymethylergoline formed in the above reaction slowly crystallized. The solution was chilled to about 0C. in order to cause more of the compound to precipitate. The solution was then filtered. and the filter cake recrystalli7ed from ethanol. A further quantity of D-6-methyl-8-mesyloxymethylergoline was obtained by extracting the filtrate with ethyl ace tate. separating the ethyl acetate layer and removing the ethyl acetate therefrom by evaporation in vacuo. Recrystallization of mesyloxymethylergoline prepared as above from ethanol yielded material melting at about l924C. with decomposition.

Analysis: Cale: C. 6l.05; H. 6.63; N. 8.38; S. 9.59; Found: C. 60.85; N. 6.46; N. 8.45: S. 9.30.

A solution of 2.5 ml. of thiophenol in ml. of DMSO was prepared. 1.1 g. of sodium methylate were added. Next a solution of 700 mg. of D-6-methyl-8 mesyloxymethylergoline in 50 ml. of DMSO was added in drop-wise fashion to the sodium thiophenate solution. After the addition had been completed. the reaction mixture was stirred at room temperature under a nitrogen atmosphere for about 2 hours. and was then poured into a saturated aqueous tartaric acid solution. The acidic layer was extracted with chloroform. The chloroform extract was separated and discarded. The acidic layer was then made basic with the excess of l4N ammonium hydroxide. and the resulting alkaline layer extracted with chloroform. The chloroform extract was separated and dried. Evaporation of the chloroform left a residue which was dissolved in ethyl acetate. The ethyl acetate solution was thoroughly washed with water followed by a wash with saturated aqueous sodium chloride solution. The ethyl acetate layer was dried. Removal of the ethyl acetate by evaporation in vacuo yielded a residue comprising D-6-methyl-8- phenylmercaptomethylergoline which was recrystallized from ethanol and melted at l945C. with do composition. The compound was then dissolved in chloroform and chromatographed over florisil (25 g. The chromatogram was developed with a chloroformmethanol (19:1) solvent mixture. Fractions containing D-6-methyl8-phenylmercaptomcthylergoline as deter mined by thin layer chromatography were combined. Evaporation ofthc solvent from the combined fractions and recrystallization of the resulting residue from an etherhexane solvent mixture yielded D-6-methyl-8- phenyhnercaptomethylergoline; MP=l95 --6C. with decomposition.

Analy is: Calc C. 75 82. H. 6.95; N. 8.04; S. 9.20; Found: C. 75.85: H. 6.69; N. 797; 9.l9.

Following the above procedure [16 methyl8- mesyloxymethyl ).Ill-didehydroergoline was reacted D-6-methyl-8- (ill 6 with thiophenol to yield D6-methyl-8- phcnylniercaptomethyl-9.lll-dideh droergoline which melted at about ZIHl -R C with decomposition after recry stalli/ation from methanol.

Analysis. Cale: C. 76.26; H. 6.40: N. 8.08. S. .15; Found: C. 76.02: H.642. N. 79915.90].

The corresponding inaleate salt was prepared by dis solving the compound in tetrahydrot'uran and adding an equivalent amount of maleic acid also in tetrahydroluran. lhc maleate salt melted at 1 8 9C. alter rccrystallixation from methanol.

Analysis: Cale: C. 67.5l: H. 5.67: N. 6.06: S. 6.93. Found: C. 67.29; H. 5.89: N. 5.79; 6.7].

EXAMPLE: 3

Preparation of D-6-methyl-8-methylmercaptomethylergolinc.

Ten milliliters of dimcthyl formamide tDMFl were cooled to about 0C. 1 ml. of methanethiol was added followed by 1.0 g. of sodium hydride as a percent suspension in mineral oil in portions. The resulting mixture was stirred for about I hour and then allowed to warm to room temperature. Then. following the procedure of Example 2. a solution of l g. of D-(vmethyl-ttmcsyloxymethylcrgoline in 50 ml. of DMF was added in drop-wise fashion to the sodium salt of methancthiol. The resulting product was isolated and purified by the procedure of Example 2 to yield D-6-methyl-8- methylmcrcaptomethylergoline melting at about l535C. Recrystallization of the compound thus ob taincd (omitting the chromatographic purification step of Example 2) from an ether-hexane solvent mixture yielded D-o-rnethyl-8-methy|mercaptomethylergolinc. MP l534C.

Analysis: Cale.: C. 7l.28'. H. 7.74; N. 9.78; S. ll.l9. Found: C. 7|.08'. H. 7.59; N. 9.83: S. 1099.

Following the above procedure D-6-methyl-8- methylmercaptomethyl-9. l U-didehydroergoline was prepared from the corresponding 8-mesyloxymethyl derivative by reaction with methylmercaptan. The compound melted at l8l-3C. with decomposition after recrystallization from ethenhexane solvent mixture.

Analysis: Cale: C. 7l.79'. H. 7.09; N. 9.85; S. 11.27: Found; C. 72.01; H. 6.84. N. 9.62; S. ll.27.

The corresponding maleate salt was prepared by dissolving the compound in ether and adding an equivalent amount of maleic acid also in ether. Maleate salt melted at l59-|60C. with decomposition.

Analysis: Calcs. C. 62.98; H. 6.07: N. 6.99; S. 8.0l; Found; C. 62.99. H. 6.l3'. N. 6.78; S. 7.86.

EXAMPLE 4 Preparation of D-6-methyl-8-acetylmerc aptomethylcrgoline Following the procedure of Example 2. thioacetie acid (as the sodium salt) was reacted with D-6-methyl- 8-mcsyloxymethylergoline in DMF solution to yield D- 6-methyl-8-aeetylmercaptomethylcrgoline which was isolated and purified by the procedure of that example. Chromatography of the crude product over florisil using chloroform containing 2 percent ethanol as eluent yielded purified D-6-metliyl-8- ricetylmcrcaptomethylergoline MP=l S3-$C. with decomposition.

Analysis: Cale: C. 68.75; H. 7.05. N. 8.91; S. I020; Found. C. 68.70; H. 7.22; N. 8.62; S. 1047.

Following the above procedure. D-(i-methyl-ticetylmercaptomethyl-J.1(l-didehydroergoline was rcpared from the corresponding S-mesyloxymethyl ompouud. The purified compound thus prepared ieltcd in the range l657C. with decomposition after ecrystallization from an ether-hexane solvent mixture.

Analysis: Calc.: C. 69.20; H. (1.45; N. 8.97: 5. 10.26; ound: C. 69.48: H. 6.71. N. 900'. S. 10.56.

The corresponding maleate salt was prepared by disolving the base in ether and adding an equivalent mount ofmaleic acid in ether. The maleatc salt melted t l789C. with decomposition.

Analysis: Cale: C. 61.67: H. 5.65: N. (1.54; S. 7.48: oundi C. 61.95; H. 5.50; N. 6.84; S. 7.63.

D2-chloro-o-mcthyl-l'lcetylmercaptomethylergoline was also prepared by he above procedure. Recrystallization of the residue emaining after combining fractions from chromatogaphy shown to contain DQ-chlorolw-methyl-8- ectylmcrcaptomcthylergoline by thin layer chroma ography. using a solvent mixture of ether and hexane or recrystallization yielded purified material melting at 40-1C.

Analysis: Cale: C. 61.97; H. 6.07; N. 8.03; S. 9.19; ,l. 10.l(i; Found: C. 61.75; H. 5.78; N. 7.75; S. 9.41. .l. 10.32.

EXAMPLE 5 rcparation of D-6-mcthyl-8-mercaptomcthylcrgolinc A reaction mixture containing 1.0 g. of D-(i-methylacctylmercaptomethylcrgolinc (from Example 4). ml. of ethanol and 100 ml. of 4N aqueous hydrohloric acid was refluxed under a nitrogen atmosphere or five and one-half hours. The reaction mixture was oolcd and made basic with an excess of MN ammoiium hydroxide. The aqueous alkaline layer was exractcd with chloroform. and the chloroform yielded a esidue comprising D-fi-methyl-S- iercaptomethylergolinc formed in the above reaction. be residue was chromatographed over 75 g. of florisil sing chloroform containing 5 percent ethanol as the luant. D-fi-mcthyl 8mercaptomethylergoline was lentificd in chromatographic fractions by thin layer hromatography as a more polar. and therefore more lowly moving. material than starting material. Frac ions containing D-6-methyl8- iercaptomethylcrgoline were combined and recrystalled from ethanol. The compound thus purified melted t 2557C. with decomposition.

Analysis: Calc.: C. 70.55; H. 7.40; N. 10.28; l 1.77; band: C. 70.31; H. 7.65. N. l0.04: S. [2.00.

The above procedure was repeated except that methlmercaptan was used in place of thioacetic acid for rection with -Zchloro-(1-methyl-8- iesyloxymethylergoline to form DQ-chloro-(i-methyl- -mcthylmcrcaptomcthylergoline. Chromatography ver florosil of the residue obtained by combining hromatographic fractions shown to contain the deircd material using an ether-hexane mixture for recrysillization yielded purified D2-chloro-6-methyl-8- iethylmercaptomethylergolinc melting at l94 5C Analysis: Cale; C. 63.63; H. 6.60; N. 8.73; S. 9.99: l. 11.05; Found: C. 63.42; H. 6.55; N. 8.47; S. 10.12:

EXAMPLE 6 Preparation of D(i-methyl-8thiocyanomethy l-9. l 0- didehydroergoline A reaction mixture containing 2.16 g. of D-(i-methyl- 8-mesyloxymcthyl-Q. l 0-didehydrocrgoline [prepared from the corresponding 8hydroxymethyl derivative by the procedure of Example I). and 2 g. of sodium thiocyanatc in 100 ml. of DMSO was heated at a temperature in the range 5070C. under a nitrogen atmosphere for about one hour. and then for an additional hour in the range -l00C. The reaction mixture was cooled. diluted with water. and the aqueous layer extracted with ethyl acetate. The ethyl acetate layer was separated and filtered to remove an insoluble purple decomposition product. The ethyl acetate layer was washed with water and with saturated aqueous sodium chloride. and was then dried. The solvent was removed therefrom by evaporation in vacuo. The resulting resi due was chromatographed over 30 g. of florisil using an eluant composed of chloroform containing 15 percent ethanol. Fractions shown to contain D-(i-meIhyLB- thiocyanomcthyl ).10-didehydrocrgolinc (formed in the above reaction] by thin layer chromatography were combined. the solvent removed therefrom. and the rc sulting residue rcchromatographcd over florisil using chloroform as an eluant. Again. fractions shown to contain D-o-methyl-R-thiocyanomethyl-Q.l0- didehydrocrgolinc by thin layer chromatography were combined and the solvent removed therefrom by evaporation. Recrystallization of the resulting residue from an ether-hexane solvent mixture yielded purified D-6- methyl 8-thiocyanomcthyl-Q.lU-didehydroergoline melting at about l-lC with decomposition.

Analysis: Cale: C. 69.12; H. 5.80; N. 14.22; S. l0.85'. Found: C. 69.03. H. 5.85. N. 14.40. S. 11.32.

Being prolactin inhibitors. the compounds of this invention are also potentially useful for suppressing the growth of breast adcnocarcinomas in female mammals. For example. D-(Hnethyl-8-thiocyanomethylergolinc has demonstrated an ability to suppress the growth of adcnocarcinomas induced by administration of dimethylbenzanthracene in female rats at a dose level of 1.2 tug/kg. The compound is administered to the female rat suspended in corn oil. although it would also be practicable to administer the compound in the form of a pharmaceutically-acceptable acid addition salt in aqueous solution.

We claim:

1. A compound of the formula:

wherein R is H. CN.

phenyl. or ulk:

R is H. Cl. or Br.

alk is C,C alkyl: and

R" and R"' when taken singly are H; and, when taken together with the carbon atoms to which they urc attached. form a double bond or u non-toxic. phurmaceuticzillyacceptahlc acid addition sult thercol'. 

1. A COMPOUND OF THE FORMULA.
 2. A compound according to claim 1, said compound being D-6-methyl-8-phenylmercaptomethyl-9,10-didehydroergoline.
 3. A compound according to claim 1, said compound being D-6-methyl-8-methylmercaptomethyl-9,10-didehydroergoline.
 4. A compound according to claim 1, said compound being D-6-methyl-8-methylmercaptomethylergoline.
 5. A compound according to claim 1, said compound being D-6-methyl-8-thiocyanomethylergoline.
 6. A compound according to claim 1, said compound being D-6-methyl-8-acetylmercaptomethylergoline. 